Bioplastics company Metabolix has devised what it hopes is an efficient way to manufacture its product: growing grass.

The company on Monday said that it has has created "significant amounts" of its bioplastic by growing it in the leaves of switchgrass. The details of the greenhouse trial are published in Plant Biotechnology Journal.

A close-up of a leaf of switchgrass with bioplastic material growing in it. The plastic will be extracted and turned into pellets. Remaining biomass can be used for other purposes such as biofuels, according to the company.

Metabolix has developed a process for making plastics by combining genes of several naturally occurring substances. It plastics, marketed under the brand Mirel, can be made from corn or other sources of sugar.

Mirel bioplastic, called polyhydroxybutyrate (PHA), are biodegradeable alternatives to petroleum plastic. A manufacturer of gardening stakes is using the plastic and it can be used for credit cards or containers of consumer products.

Growing the plastic in a plant will allow for the switchgrass to produce both bioplastics and use residual biomass for energy, according to the company. The plastic would be culled and turned into pellets for plastic production.

Switchgrass is a perennial native grass that grows quickly. Researchers and several companies are developing methods for converting the plant biomass into ethanol.

"This result validates the prospect for economic production of PHA polymer in switchgrass, and demonstrates for the first time an important tool for enhancing switchgrass for value-added performance as a bioenergy crop," Oliver Peoples, chief scientific officer, said in a statement.

Last year, company executives said that they expected that their process for growing plastics would be commercial by 2012.

A number of bio-energy companies are looking at bioplastics production. Earlier this month, energy crop company Ceres said that it intends to use genetic engineering to grow plastics directly in plants as well.

Update on August 13, 1:50 p.m. PT with different photo of switchgrass leaf.